linux-kernel - Re: [PATCH][RSDL-mm 0/7] RSDL cpu scheduler for 2.6.21-rc3-mm2

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Date:	Tue, 13 Mar 2007 05:10:05 +1100
From:	Con Kolivas <kernel@...ivas.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	ck list <ck@....kolivas.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH][RSDL-mm 0/7] RSDL cpu scheduler for 2.6.21-rc3-mm2

On Tuesday 13 March 2007 02:26, Linus Torvalds wrote:
> On Mon, 12 Mar 2007, Mike Galbraith wrote:
> > On Mon, 2007-03-12 at 22:23 +1100, Con Kolivas wrote:
> > > Mike the cpu is being proportioned out perfectly according to fairness
> > > as I mentioned in the prior email, yet X is getting the lower latency
> > > scheduling. I'm not sure within the bounds of fairness what more would
> > > you have happen to your liking with this test case?
> >
> > It has been said that "perfection is the enemy of good".  The two
> > interactive tasks receiving 40% cpu while two niced background jobs
> > receive 60% may well be perfect, but it's damn sure not good.
>
> Well, the real problem is really "server that works on behalf of somebody
> else".
>
> X is just the worst *practical* example of this, since not only is it the
> most common such server, it's also a case where people see interactive
> issues really easily.
>
> And the problem is that a lot of clients actually end up doing *more* in
> the X server than they do themselves directly. Doing things like showing a
> line of text on the screen is a lot more expensive than just keeping track
> of that line of text, so you end up with the X server easily being marked
> as getting "too much" CPU time, and the clients as being starved for CPU
> time. And then you get bad interactive behaviour.
>
> So "good fairness" really should involve some notion of "work done for
> others". It's just not very easy to do..

Instead of assuming it's bad, have you tried RSDL for yourself? Mike is using 
2 lame threads for his test case.

-- 
-ck
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